With the development of bioengineering, drugs are no longer limited to traditional chemical drugs. More and more attention has been paid to biological drugs with a wide range of sources and low toxicity. In the past, the development of new drug delivery systems has received significant attention. A successful drug delivery system can improve the stability of biological drugs, achieve the targeted effect of drugs through special targeted materials, and reduce the toxic and side effects. In particular, vesicles have outstanding advantages in delivering biological drugs such as protein peptides, nucleic acids, hormones, etc. Using vesicles for delivery can improve drug solubility, enhance drug stability, delay drug release, and achieve high efficiency and low toxicity.

The vesicular system is an efficient method for reducing drug toxicity and targeting it to the site of action. A vesicular drug delivery system (VDDS) is the system in which encapsulation of active moieties in vesicular structure, which bridges the gap between ideal and available of novel drug delivery system. This system has some advantages, such as prolonging the existence of the drug in systemic circulation, improving the bioavailability of poorly soluble drugs, delaying the elimination of rapidly metabolizing drugs, etc. Various types of vesicular drug delivery systems have been developed, including liposomes, niosomes, transfersomes, pharmacosomes, etc.

Liposomes
Liposomes are colloidal, concentric bilayered vesicles made up of biodegradable natural or synthetic phospholipids, which can encapsulate, deliver and release low-soluble drugs and small molecules to a specific target site in the body. Liposomes are a well-established formulation strategy to improve drug delivery and enhance therapeutic outcomes for a range of drugs, such as pharmaceuticals, biopharmaceuticals, and vaccines.

Liposomes have been shown to have protective effects against proteolytic digestive enzymes such as pepsin and pancreatin, increasing the intestinal uptake of macromolecules and thus enhancing insulin uptake. Therefore, liposomes can be used as a delivery system for the oral administration of insulin.

Niosomes
Niosomes are a nanoparticular delivery system, in which the medication is encapsulated in a vesicle. Considering cost, stability, entrapment efficiency, bioavailability, biodegradability, nontoxicity, and other factors, niosomes are expected to become better drug carrier systems than liposomes. Niosomes have a wide range of applications in the pharmaceutical field. Some of the most important uses are as gene delivery carriers, hemoglobin carriers, and vaccine delivery carriers.

Transfersomes
Liposomal as well as niosomal systems, are not suitable for transdermal delivery of drugs, because of their poor skin permeability, breaking of vesicles, leakage of drug, aggregation, and fusion of vesicles. To solve these problems, a new type of carrier system called “transfersome”, has recently been introduced.

Transfersomes have been proposed for a variety of applications in humans. Transfersomes can be used for the delivery of various active compounds, including proteins and peptides, insulin, corticosteroids, interferons, anesthetics, NSAIDs, anticancer drugs and herbal drugs.

Pharmacosomes
Pharmacosomes are amphiphilic phospholipid complexes of drugs bearing active hydrogen that bind to phospholipids. They possess the characteristics of small size, amphiphilicity, drug loading activity, high encapsulation efficiency and good stability, which are suitable for the delivery of precision medicine.